Pilot controlled piston type reversing valve



Nov. 27, 1956 J. F. JOY 2,771,907

PILOT CONTROLLED PISTON TYPE REVERSING VALVE Original Filed Jan. 29.1949 4 Sheets-Sheet l J. F. JOY 2,771,907

PILOT coN'rRoLLED PIsToN TYPE REvERsING VALVE Nov. 27, 1956 4Sheets-Sheet 2 Original Filed Jan, 29, 1949 @MSH Crt Q ATTORNEY J. F.JOY

Nov. 27, 1956 PILOT CONTROLLED PISTON TYPE REVERSING VALVE 4Sheets-Sheet 5 Original Filed Jan'. 29. 1949 1 #wwf Nov. 27, 19,56 J. F.JoY 2,771,907

PILOT CONTROLLED PIsToN TYPE REVERSING VALVE- original Filed Jan. 29,194e 4 sheets-snee#L 4 JOSE/0H fic/Uy y United States Patent O PILOTCONTROLLEDPISTON TYPE REVERSING VALVE Joseph F. Joy, Pittsburgh, Pa.,assigner to Joy Manufacturing Company, Pittsburgh, Pa., -a corporationof Penn- Sylvania Original application January 29, 1949, Serial No.73,625.

Divided and this application September 27, 1951, Serial No. 248,573

2 Claims. (Cl. 137-622) This invention relates to a reversing valve forhydraulic systems, and is a divisi-on of my application Serial No.73,625, led January 29, 1949, now Patent No. 2,696,906, of December 14,1954.

Hydrauiic systems involving .a hydraulic motor which reverses directionperiodically, conventionally employ a reversing valve of some sort toreverse the direction of fluid ilow. The action of such reversing valvesmust be quick, and they must be reliable. Many valves now in use in suchsystems are subject to the objectionable defeet `of stickingf meaningseizure of the moving parts to the extent of preventing such relativemovement as is necessary :to successful operation. When such a valvesticks, the human operator, often an unskilled workman, is likely to jarthe moving parts loose by striking the valve housing a sharp blow with ahammer. Obviously, such treatment, especially when repeated often, isalmost certain Ito result in distortion of the carefully machined andalined cooperating surfaces, and in eventual damage to the extent ofmaking the valve useless.

It is accordingly an object of this invention to provide a reversingvalve for a fluid system which operates quickly and reliably :and whichis not subject to such seizure of the moving parts as will render thevalve inopera-tive unless struck a blow from an external source. Thisand other objects are accomplished in a valve having a pilot memberwhich is externally actuated and which engages and positively moves themain valve member should it stick momentarily.

In the drawings: f

Fig. l is a longitudinal sectional view through the reversing valveshowing the valve in a neutral position.

Fig. 2 is a view in section on line 2-2 of Fig. 1.

Fig. 3 is another longitudinal sectional view of the reversing valve butwith the plane of the section being perpendicular to the plane of thesection yof Fig. l and showing the valve Vin another position.

Fig. 4 is .a view similar to Fig. 3, showing the valve in an operatingposition in which iluid is admitted to one end thereof to shift thevalve to another operating position.

Figs. 5 and 6 are sectional views similar to Fig. 3 but showing thevalve in other operating positions.

Fig. 7 is an enlarged detail view of a portion of the valve as shown inFig. 6, but on a much larger scale.

The reversing valve will now be described in detail. A substantiallycylindrical shell 2 is provided with an internal bore 4 and a pluralityof internal grooves 6, S, 10, 12, and 14, The grooves communicaterespectively with a low pressure iluid connection 16, a pressure-fluidconduit 18, a high pressure fluid connection 20, a pressure-fluidconduit 22, and a low pressure uid connection 24. lf desired, the valvecould be made with the grooves communicating directly with the bore, buta preferred form of construction is that shown, in which a sleeve 26snugly tits the bore 4 of the shell 2.

Sleeve 26 is provided with a plurality of sets of ports 28, 30, 32, 34,and 36, which communicate respectively 2,771,907 Patented Nov. 27, 1956with grooves 6, 8, 10, k12, and 14. Thus, in the preferred embodiment ofthe invention, communication between two or more grooves is by way ofthe interior of sleeve 26 and the associated ports, The sleeve 26 isremovably secured in bore 4 by means of end caps 38 and 40. These capsare held in place by any suitable means such as threaded members 42passing through the end caps and engaging the shell 2.

A hollow elongated main valve member 44 is re-l ciprocably mounted inthe sleeve 26. Main valve member 44 is provided with end pistons 46 and43 and a plurality of port closers Sil and 52 between the en d pistons46 and 43. In the embodiment shown, the end pistons and port closers areof substantially the same external diameter as, and cooperate with, theinside diameter of the sleeve 26 to open and close .certain of thesleeve ports. As is best seen in Fig. l, port closets `50 and 52preferably have :a dimension in the axial direction which is sucient toclose a port when the port closer is alined therewith. It will be notedfurther that the main valve member 44 is itself provided with ports 54,56 and 58. When the valve is in the central position shown `in Fig. l,these po-rts are alined with vports 28, 32, and 36 respectively.

It was pointed out above that the main valve member 44 is hollow. Thishollow consists of -an internal bore 6d in which a pilot valve memberindicated generally at 62 is mounted for reeiprocation, The pilot valvemember consists of a hollow elongated element 464, of which the hollow66 is blocked substantially midway between its ends by a plug 68 held inplace by means of pins 70.

The elongated member is provided `at its exterior with port closers 72,74, and 76. These port closers are .in effect the lands of a spool whichtill up'y the internal bore 60 -o-f the main valve vmember and thusserve to block fluid passage in an axial direction through the mainvalve member. in addition, the elongated member is provided with endpistons 78 and 8d which also havean external diameter such as to bereciprocable in andsubstantially block the internal bore 60 of the mainvalve member. As is best seen in Fig. 7, the'end pistons 78 and 80 `arepreferably somewhat smaller than bore 60 to provide a clearance S2 andto permit a throttling etfectkin operation. The hollow elongatedelementof the `pilot valve member is further provided with ports oriluidpassages 84 and 86 at opposite sides of the plug 68 and with radialluid passages 88 and 99 at its ends.

An actuating rod 94 threadedly yengages the -end 96 of the pilot valvemember and a guide vrod 9.8 threadedly engages the opposite end 191i yofthe pilot valve member. A suitable lock nut y192 engages each of thethreaded portions of rods 94 and 98 to guardragainst loosening of thethreaded connections. As will be well understood by those skilled in theart, the rods 94 and 98 pass through stuffing boxes 104, of which thepacking and gland are secured between a anged member 106 and a stuingbox cap 103. The flanged member 106 engages an end of sleeve 26 and alsoserves to hold a seal 110 in place in an annular recess provided for thepurpose in each of end caps 38 and 4t).

Operation Let it be lassumed that the description of the operationbegins with the main valve member and the pilot valve member at theextreme right limits of travel (Fig. 3). Let it further be assumed thatthe hydraulic system is nearing the end of one phase of operation, atwhich time the valve must be reversed. At the appropriate time, suitableactuating mechanism pulls the pilot valve member leftward from theposition shown in Fig. 3 into the operating position shown in Fig. 4.Thereupon, uid under high pressure is admitted from the high pressurefluid connection into groove 10, whence it passes through ports 32 inthe sleeve 26, ports 56 in the main valve member, into the annular spacebetween the main valve member and the pilot valve member, through ports86 in the pilot valve member, along the right half of the hollow pilotvalve member, and out through radial ports '90 in the end 100 of thepilot valve member, whereupon fluid at high pressure is admitted to theright end of main valve member 44 and'also the right end of the pilotvalve member.

Also, with the parts in this position, the left end of the main valvemember is open to the low pressure fluid connection 16 by way of theannular passage between the main valve member and the pilot valvemember, ports 54 the main valve member, ports 28 in the sleeve, andgroove 6. With the high fluid pressure at the right end of the mainvalve member and the pilot valve member, and low pressure at the leftend, the system is unbalanced so far as pressure is concerned. As aresult, the main valve member and pilot valve member move rapidlytowardthe left into the position shown in Figs. 6 and 7. The pilot valvemember will reach the end of its travel first, and as the main valvemember nears the end of its travel, end piston 78 enters the end of bore60. The clearance 82 provides a throttling effect which cushions thestopping of the main valve member. If the main valve member should stickmomentarily, it will be moved positively toward the left mechanically bythe pilot valve member, as shown in Fig. 5. After it is thus started,the valve can be moved by the fluid pressure acting as aforesaid.

It will be apparent to those skilled in the art that I have hereprovided a reversing valve having numerous advantages, among which isreliability of operation due to a positive movement of the main valvemember in case of seizure or sticking, after which movement is continuedby the fluid pressure acting in the manner set forth. Other advantageswill be apparent to those skilled in the art.

While there is in thisy application specifically described one formwhich the invention may assume in practice, it will be understood thatthis form of the same is shown for purposes of illustratiornand that theinvention may be modified and embodied in various other forms withoutdeparting from its spirit or the scope of the appended claims.

I claim:

l. In a reversing valve, a shell having an internal bore and a pluralityof fluid passages through the shell, means for conducting a fluid underpressure to said shell, a hollow main valve member reciprocable in theshell and having at least one actuating piston and a means to preventcommunication between certain passages and permit communication betweencertain passages according to its position, and a pilot valve memberreciprocable in the main ve member `and having at least one actuatingpiston,

and a meansfor preventing and for permitting communication between saidfluid under pressure and said one main valve actuating piston and saidone pilot valve actuating piston means for moving said pilot valverelative to said main valve to provide communication between said fluidpressure conducting means and said one main valve actuating piston andsaid one pilot valve actuating piston to move said valves in onedirection relative to said shell, means on said pilot valve for engagingsaid main valve to initiate movement of the latter if said fluid underpressure fails to vdo so and for striking said main valve at any pointsubstantially 4throughout its distance of travel, if its movement isretarded, to urge it in said one direction of travel, and' means tocushion the stopping of the main valve member by throttling including anend piston on said pilot valve spaced from said one pilot valveactuating piston and smaller than the hollow of said main valve member.

2. In a reversing valve, a shell having an internal bore and a pluralityof fluid passages through the shell, means for conducting a fluid underpressure to said shell, a hollow main valve member reciprocable in theshell and having a pair of actuating pistons spaced apart longitudinallyof said main valve member and a means to prevent communication betweencertain passages and permit communication between certain passagesaccording to its position, and a pilot valve member reciprocable in themain valve member and having a pair of actuating pistons smaller thanthe hollow of said main valve member and spaced apart longitudinally ofsaid pilot valve member and a means for preventing and for permittingcommunication between said fluid under pressure and said main valveactuating pistons and said pilot valve actuating pistons, means formovingsaid pilot valve relative to said main valve to providecommunication between said fluid pressure conducting means and one ofsaid main valve actuating pistons and one of said pilot valve actuatingpistons to move said valves in one direction relative to said shell,means on said pilot valve for engaging said main valve to initiatemovement of the latter if said fluid under pressure fails to do so andfor striking said main valve at any point substantially throughout itsdistance of travel, if its movement is retarded, to urge it in said onedirection of travel, and means including the other of said pilot valvepistons to cushion the stopping of the main valve member by throttling.

References Cited in the file of this patent UNITED STATES PATENTS292,541 Craig Ian. 29, 1884 663,135 Spencer Dec. 4, 1900 927,560 LewisJuly 13, 1909 992,161 Catlin May 16, 1911 2,361,757 Fink Oct. 31, 1944

